1. Field
The invention is in the field of apparatus and methods for automatically sorting mixed items and for removing those items which do not conform to predetermined standards. It is specifically concerned with the automatic sorting of items, such as pieces cut from peeled, raw, white potatoes in the production of commercially prepared food products, to eliminate defective items.
2. State of the Art
There are numerous machines described in the patent literature for sorting such items as fruits and vegetables. Many of these machines use light sources to illuminate the items to be sorted. In some cases the translucence of an item is a measure of its condition, defective items exhibiting different translucence than sound items. In such cases, light sensors are arranged to detect the light transmitted by the items being sorted. In other cases, the amount of light reflected from an item is a measure of its condition. In those cases, sensors are arranged to detect reflected light. In still other cases, the color of an item indicates its condition. In these other cases, reflected light of a certain wavelength is detected by light sensors, and associated filters are provided to pass to the sensors only reflected light of that wavelength.
A U.S. patent issued July 11, 1972, as U.S. Pat. No. 3,675,769, discloses a sorting system that detects ratios of reflected light of two wavelength ranges in order to differentiate between field-dug potatoes and rocks and dirt clods as the potatoes are being harvested. With this system, as with the color sorting systems mentioned which detect light within restricted wavelength ranges, the individual items to be sorted are segregated into longitudinal rows, down which they pass single file and are viewed individually as they pass.